1. Field of the Invention
The invention is directed to a DC/DC converter circuit with feedback capability for connection to a DC voltage source and a DC voltage sink, wherein the preferred energy transport takes place from the DC voltage source to the DC voltage sink. As used herein, the term “with feedback capability” also describes the opposite path and, therefore, the DC/DC converter circuit can also transport energy from the DC voltage sink to the DC voltage source. Furthermore, the invention is also directed to an advantageous method for operation of such a DC/DC converter circuit.
2. Description of the Related Art
DC/DC converter circuits such as described, DC/DC converter cell arrangements which inter alia form them, and DC/DC converter cells which form them are in general used for voltage matching of the output voltage of a DC voltage source whose output voltage may vary over time to a DC voltage sink at a voltage level which is constant over time and is, in general, higher than the voltage source.
DC voltage sources of this type may be, for example, photovoltaic systems or subsystems thereof, fuel cells or storage elements such as rechargeable batteries or capacitor circuits. The various functional parameters are typical for the various types of DC voltage sources. While photovoltaic systems are essentially characterized in that their output voltage may be subject to major fluctuations, fuel cells are characterized by a relatively constant voltage output. Various storage elements have a generally constant output voltage, although this is naturally limited over time, referred to in a better form here as terminal voltages.
DC voltage sinks may be the input of an inverter circuit arrangement or a DC bus system. A DC bus system typically has a plurality of DC/DC converter systems of the same type or in different forms connected to them, with DC voltage sources connected to them, which either feed the DC bus system, or are fed from it. Accounting for line losses, it is frequently advantageous to choose the voltage level of the DC bus system to be considerably higher than the output voltage of at least most of the connected DC voltage sources.